diff --git a/lisp/info-look.el b/lisp/info-look.el
index 7f45f976a24..ce0a08dcbe6 100644
--- a/lisp/info-look.el
+++ b/lisp/info-look.el
@@ -130,7 +130,8 @@ OTHER-MODES is a list of cross references to other help modes.")
 (defun info-lookup--expand-info (info)
   ;; We have a dynamic doc-spec function.
   (when (and (null (nth 3 info))
-             (nth 6 info))
+             (nth 6 info)
+             (functionp (nth 6 info)))
     (setf (nth 3 info) (funcall (nth 6 info))
           (nth 6 info) nil))
   info)